On Thu, Oct 24, 2024 at 09:11:04AM +0200, Philipp Rosenberger wrote: > On 22.10.24 18:35, Conor Dooley wrote: > > On Tue, Oct 22, 2024 at 11:28:54AM +0200, Philipp Rosenberger wrote: > > > The nxp,battery-switch-over property is used to control the switch-over, > > > battery low detection and extra power fail detection functions. > > > > > > The PCF2131 has a different default value for the PWRMNG bits. It is set > > > to 0x7: battery switch-over function is disabled, only one power supply > > > (VDD); battery low detection function is disabled. > > > This is the opposite of the default of the PCF2127/PCA2129 and PCF2129. > > > With the nxp,battery-switch-over the behavior can be controlled through > > > the device tree. > > > > > > Signed-off-by: Philipp Rosenberger <p.rosenberger@xxxxxxxxxx> > > > --- > > > Documentation/devicetree/bindings/rtc/nxp,pcf2127.yaml | 10 ++++++++++ > > > 1 file changed, 10 insertions(+) > > > > > > diff --git a/Documentation/devicetree/bindings/rtc/nxp,pcf2127.yaml b/Documentation/devicetree/bindings/rtc/nxp,pcf2127.yaml > > > index 2d9fe5a75b06..5739c3e371e7 100644 > > > --- a/Documentation/devicetree/bindings/rtc/nxp,pcf2127.yaml > > > +++ b/Documentation/devicetree/bindings/rtc/nxp,pcf2127.yaml > > > @@ -30,6 +30,16 @@ properties: > > > reset-source: true > > > + nxp,battery-switch-over: > > > + description: > > > + Battery and power related configuration. This property is used to set the > > > + PWRMNG bits of the Control_3 register to control the battery switch-over, > > > + battery low detection and extra power fail detection functions. > > > + The actual supported functions depend on the device capabilities. > > > + $ref: /schemas/types.yaml#/definitions/uint8 > > > + minimum: 0 > > > + maximum: 7 > > > > Beyond the fact that I dislike register-content properties like this, where > > it is not possible to grok the meaning by reading the property, what > > Yes, I'm not satisfied with this solution myself. > There are three different functions, which can be configured in the > register: > - battery switch-over mode: standard; direct; disabled > - battery low detection: enabled; disabled > - extra power fail detection: enabled; disabled > > I'm not sure what a proper way is to implement this in the devicetree. > > > even makes this suitable for DT in the first place? Reading the commit > > message this sounds like software policy, and that different users of > > the same board might want to configure these register bits in different > > ways. > > It is less a software policy, but a configuration how the hardware is > implemented. If the device has no battery, it is possible to disable the > battery switch-over function. In this case the V_BAT must be connected to > ground. monitored-battery property already tells you this. > If a battery is connected, the battery switchover will only work if the > battery switch-over function is in standard mode or direct switching mode. > Until now the driver has just ignored the PWRMNG bits. As the default was > battery switching in standard mode. Thus all use cases worked good enough. > Battery switching was working if a battery was connected. If no battery was > connected it did no real harm (the rtc may have used a tiny bit more power > then needed, I guess). Why driver cannot use standard mode always? Or other way? > With the new PCF2131 the default has changed to battery switch-over > disabled. Now even with a battery attached, the rtc will lose time after a > power cycle. > I guess I should describe this better in the commit message. In any case this is pcf2131 related, right? So compatible implies it. Best regards, Krzysztof
